1. Field of the Invention
The present invention relates generally to overhead ventilation systems for use with ovens and other cooking appliances and, more particularly, to a ventilator hood for removing heat, airborne grease and smoke from such cooking appliances which incorporate a fixed blade damper so as to create an airflow equilibrium within the hood so as to minimize the loss of quality interior air.
2. Description of the Prior Art
The prior art is well documented with ventilation hoods utilized in ventilation systems for facilitating the removal of heat, airborne grease and smoke from the cooking devices, and in particular commercial cooking equipment such as ranges, pizza ovens and the like. The objective of each such ventilation system is the ability to evacuate the undesirable by-products of the cooking appliance in such a manner so as not to affect the air quality established within the room enclosure surrounding the oven. This is preferably accomplished by providing a separate air inlet to the ventilation hood in addition to the exhaust outlet in the attempt to achieve an air equilibrium condition within the hood so as not to evacuate the quality conditioned (heated or cooled) air within the surrounding room enclosure.
U.S. Pat. No. 5,713,346, issued to Kuechler, discloses an exhaust hood ventilating system which utilizes both intake and exhaust blowers and means for regulating the volume of air introduced within the ventilation hood. Additional means are disclosed for creating a vortex flow within the hood enclosure and for diverting outdoor intake air into a surrounding kitchen area for ventilation before it is passed back to the hood for exhaust to the outdoors.
U.S. Pat. No. 5,467,761, also issued to Kuechler, teaches a further variation of a filtering apparatus in which a supply air plenum is provided with perforated balancing plates and deflector plates which perform the functions of modulating an incoming air flow. A filter is arrayed in proximity to an exhaust of the apparatus to facilitate removal of the by-products of appliance.
U.S. Pat. Nos. 4,944,285 and 4,896,657, both issued to Glassman, teach variations of an exhaust hood for a pizza oven which induces exhaust materials into the exhaust stream by creating high velocity flow of outside air into the hood. According to the '285 patent, an intake fan forces outside air into a pair of intake plenums located along opposite sides of the hood, creating two high velocity air streams flowing toward a central exhaust plenum and an exhaust fan drawing air into the exhaust plenum and through inclined grease filters. According to the '657 patent, a central intake fan forces outside air into a central intake plenum and through air deflectors to redirect opposite extending air streams through exhaust plenums on opposite sides of the hood. Exhaust fan draw air into the exhaust plenums and through inclined grease filters.
U.S. Pat. No. 4,655,194, issued to Wooden, teaches a system which includes a hood enclosure having a horizontally arrayed distribution baffle including adjustable diffusion baffle plates. A secondary filter constructed of three or more individual filter layers is mounted to a rearside of the baffle plates and the baffle functions to introduce an intake stream of air in a substantially downwardly extending fashion within and beneath the hood enclosure so as to intermix with rising heat and other undesirable by-products given off by the cooking appliance and prior to additional filtering at the outlet stage and prior to evacuation through an exhaust leading from the hood enclosure.
A shortcoming of the prior art is the inability to create a controlled equilibrium environment within a ventilation hood assembly for facilitating the evacuation of heat, airborne grease, smoke and odors emitted from the cooking appliance while at the same time preventing the loss of quality interior conditioned air through the hood exhaust or the substantial introduction of outside supply air past the hood enclosure and within the room interior. A further shortcoming is the inability to adjust the rate of flow of inlet air into the hood to such a degree of accuracy so as to equal or control the supply flow of air.